Treatment for depression is a core health disparity for Latinos in the U.S. Although U.S. Latinos are more likely than non-Hispanic Whites to experience depression (Alegria et al., 2006), U.S. Latinos are less than half as likely as Whites to receive evidence-based care for depression (Lagomasino et al., 2014). Latinos with elevated depressive symptoms are most likely to report such symptoms to primary care physicians (PCPs; Lewis-Fernandez et al., 2005), who in turn typically prescribe antidepressant medication and rarely recommend psychotherapy. This limited recommendation of psychotherapy is problematic because, as compared to Whites, Latinos: 1) are less likely to take antidepressant medication when prescribed (Miranda & Cooper, 2004) and 2) prefer psychotherapy as compared to medication for the treatment of depression (Cooper et al., 2003). Thus, in order to reduce the depression treatment disparity for Latinos, the dissemination of evidence-based therapies for depression via PCPs must be improved. Mobile technologies, including smartphones and mobile applications (apps) are widely used by Latinos in the U.S. and offer an ideal vehicle for meeting widespread treatment needs. As behavior therapies have demonstrated efficacy for the treatment of depression among Latino patients (e.g., Collado et al., 2014), these therapies are natural fits when selecting a treatment to adapt for delivery via a mobile app and recommendation by a PCP. One behavior therapy that is especially appropriate for this group is brief Behavioral Activation (BA; Lejuez et al., 2001; Collado et al., 2014). Considering that Latinos in the U.S. are a heterogenous group, brief BA is an ideal fit because it is idiographic, affords the accommodation of personal values on an individual basis, and can be delivered in Spanish. Moreover, brief BA is appropriate for delivery via a mobile app and for recommendation by a PCP because it is simple, straightforward, and evidence-based. In this Phase I STTR, we will leverage our previous research in order to develop, test, and refine a Spanish-language mobile app version of brief BA (Apptivacin Conductual) in the service of increasing access to evidence-based depression treatment for Latinos. We will conduct a small-scale randomized clinical trial with 40 U.S. Latino adults with limited English proficiency and elevated depressive symptoms referred from local PCPs, who will be randomized to receive either Apptivacin Conductual or a CBT-based Spanish- language mobile app (iCouch CBT). Key outcomes include treatment feasibility, acceptability, adherence, and change in depressive symptoms associated with Apptivacin Conductual as compared to iCouch CBT. Via product development, testing, and refinement consistent with the STTR Phase I mechanism, we expect to create a marketable product for which we will pursue larger scale clinical testing in an STTR Phase II study.